drivers/spi/spi-clps711x.c

   1 /*
   2  *  CLPS711X SPI bus driver
   3  *
   4  *  Copyright (C) 2012-2014 Alexander Shiyan <shc_work@mail.ru>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  */
  11
  12 #include <linux/io.h>
  13 #include <linux/clk.h>
  14 #include <linux/gpio.h>
  15 #include <linux/delay.h>
  16 #include <linux/module.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/regmap.h>
  20 #include <linux/mfd/syscon.h>
  21 #include <linux/mfd/syscon/clps711x.h>
  22 #include <linux/spi/spi.h>
  23 #include <linux/platform_data/spi-clps711x.h>
  24
  25 #define DRIVER_NAME     "spi-clps711x"
  26
  27 #define SYNCIO_FRMLEN(x)        ((x) << 8)
  28 #define SYNCIO_TXFRMEN          (1 << 14)
  29
  30 struct spi_clps711x_data {
  31         void __iomem            *syncio;
  32         struct regmap           *syscon;
  33         struct regmap           *syscon1;
  34         struct clk              *spi_clk;
  35
  36         u8                      *tx_buf;
  37         u8                      *rx_buf;
  38         unsigned int            bpw;
  39         int                     len;
  40 };
  41
  42 static int spi_clps711x_setup(struct spi_device *spi)
  43 {
  44         /* We are expect that SPI-device is not selected */
  45         gpio_direction_output(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
  46
  47         return 0;
  48 }
  49
  50 static void spi_clps711x_setup_xfer(struct spi_device *spi,
  51                                     struct spi_transfer *xfer)
  52 {
  53         struct spi_master *master = spi->master;
  54         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
  55
  56         /* Setup SPI frequency divider */
  57         if (xfer->speed_hz >= master->max_speed_hz)
  58                 regmap_update_bits(hw->syscon1, SYSCON_OFFSET,
  59                                    SYSCON1_ADCKSEL_MASK, SYSCON1_ADCKSEL(3));
  60         else if (xfer->speed_hz >= (master->max_speed_hz / 2))
  61                 regmap_update_bits(hw->syscon1, SYSCON_OFFSET,
  62                                    SYSCON1_ADCKSEL_MASK, SYSCON1_ADCKSEL(2));
  63         else if (xfer->speed_hz >= (master->max_speed_hz / 8))
  64                 regmap_update_bits(hw->syscon1, SYSCON_OFFSET,
  65                                    SYSCON1_ADCKSEL_MASK, SYSCON1_ADCKSEL(1));
  66         else
  67                 regmap_update_bits(hw->syscon1, SYSCON_OFFSET,
  68                                    SYSCON1_ADCKSEL_MASK, SYSCON1_ADCKSEL(0));
  69 }
  70
  71 static int spi_clps711x_prepare_message(struct spi_master *master,
  72                                         struct spi_message *msg)
  73 {
  74         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
  75         struct spi_device *spi = msg->spi;
  76
  77         /* Setup mode for transfer */
  78         return regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCKNSEN,
  79                                   (spi->mode & SPI_CPHA) ?
  80                                   SYSCON3_ADCCKNSEN : 0);
  81 }
  82
  83 static int spi_clps711x_transfer_one(struct spi_master *master,
  84                                      struct spi_device *spi,
  85                                      struct spi_transfer *xfer)
  86 {
  87         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
  88         u8 data;
  89
  90         spi_clps711x_setup_xfer(spi, xfer);
  91
  92         hw->len = xfer->len;
  93         hw->bpw = xfer->bits_per_word;
  94         hw->tx_buf = (u8 *)xfer->tx_buf;
  95         hw->rx_buf = (u8 *)xfer->rx_buf;
  96
  97         /* Initiate transfer */
  98         data = hw->tx_buf ? *hw->tx_buf++ : 0;
  99         writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN, hw->syncio);
 100
 101         return 1;
 102 }
 103
 104 static irqreturn_t spi_clps711x_isr(int irq, void *dev_id)
 105 {
 106         struct spi_master *master = dev_id;
 107         struct spi_clps711x_data *hw = spi_master_get_devdata(master);
 108         u8 data;
 109
 110         /* Handle RX */
 111         data = readb(hw->syncio);
 112         if (hw->rx_buf)
 113                 *hw->rx_buf++ = data;
 114
 115         /* Handle TX */
 116         if (--hw->len > 0) {
 117                 data = hw->tx_buf ? *hw->tx_buf++ : 0;
 118                 writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN,
 119                        hw->syncio);
 120         } else
 121                 spi_finalize_current_transfer(master);
 122
 123         return IRQ_HANDLED;
 124 }
 125
 126 static int spi_clps711x_probe(struct platform_device *pdev)
 127 {
 128         struct spi_clps711x_data *hw;
 129         struct spi_clps711x_pdata *pdata = dev_get_platdata(&pdev->dev);
 130         struct spi_master *master;
 131         struct resource *res;
 132         int i, irq, ret;
 133
 134         if (!pdata) {
 135                 dev_err(&pdev->dev, "No platform data supplied\n");
 136                 return -EINVAL;
 137         }
 138
 139         if (pdata->num_chipselect < 1) {
 140                 dev_err(&pdev->dev, "At least one CS must be defined\n");
 141                 return -EINVAL;
 142         }
 143
 144         irq = platform_get_irq(pdev, 0);
 145         if (irq < 0)
 146                 return irq;
 147
 148         master = spi_alloc_master(&pdev->dev, sizeof(*hw));
 149         if (!master)
 150                 return -ENOMEM;
 151
 152         master->cs_gpios = devm_kzalloc(&pdev->dev, sizeof(int) *
 153                                         pdata->num_chipselect, GFP_KERNEL);
 154         if (!master->cs_gpios) {
 155                 ret = -ENOMEM;
 156                 goto err_out;
 157         }
 158
 159         master->bus_num = pdev->id;
 160         master->mode_bits = SPI_CPHA | SPI_CS_HIGH;
 161         master->bits_per_word_mask =  SPI_BPW_RANGE_MASK(1, 8);
 162         master->num_chipselect = pdata->num_chipselect;
 163         master->setup = spi_clps711x_setup;
 164         master->prepare_message = spi_clps711x_prepare_message;
 165         master->transfer_one = spi_clps711x_transfer_one;
 166
 167         hw = spi_master_get_devdata(master);
 168
 169         for (i = 0; i < master->num_chipselect; i++) {
 170                 master->cs_gpios[i] = pdata->chipselect[i];
 171                 ret = devm_gpio_request(&pdev->dev, master->cs_gpios[i],
 172                                         DRIVER_NAME);
 173                 if (ret) {
 174                         dev_err(&pdev->dev, "Can't get CS GPIO %i\n", i);
 175                         goto err_out;
 176                 }
 177         }
 178
 179         hw->spi_clk = devm_clk_get(&pdev->dev, "spi");
 180         if (IS_ERR(hw->spi_clk)) {
 181                 dev_err(&pdev->dev, "Can't get clocks\n");
 182                 ret = PTR_ERR(hw->spi_clk);
 183                 goto err_out;
 184         }
 185         master->max_speed_hz = clk_get_rate(hw->spi_clk);
 186
 187         hw->syscon = syscon_regmap_lookup_by_pdevname("syscon.3");
 188         if (IS_ERR(hw->syscon)) {
 189                 ret = PTR_ERR(hw->syscon);
 190                 goto err_out;
 191         }
 192
 193         hw->syscon1 = syscon_regmap_lookup_by_pdevname("syscon.1");
 194         if (IS_ERR(hw->syscon1)) {
 195                 ret = PTR_ERR(hw->syscon1);
 196                 goto err_out;
 197         }
 198
 199         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 200         hw->syncio = devm_ioremap_resource(&pdev->dev, res);
 201         if (IS_ERR(hw->syncio)) {
 202                 ret = PTR_ERR(hw->syncio);
 203                 goto err_out;
 204         }
 205
 206         /* Disable extended mode due hardware problems */
 207         regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCON, 0);
 208
 209         /* Clear possible pending interrupt */
 210         readl(hw->syncio);
 211
 212         ret = devm_request_irq(&pdev->dev, irq, spi_clps711x_isr, 0,
 213                                dev_name(&pdev->dev), master);
 214         if (ret)
 215                 goto err_out;
 216
 217         ret = devm_spi_register_master(&pdev->dev, master);
 218         if (!ret) {
 219                 dev_info(&pdev->dev,
 220                          "SPI bus driver initialized. Master clock %u Hz\n",
 221                          master->max_speed_hz);
 222                 return 0;
 223         }
 224
 225         dev_err(&pdev->dev, "Failed to register master\n");
 226
 227 err_out:
 228         spi_master_put(master);
 229
 230         return ret;
 231 }
 232
 233 static struct platform_driver clps711x_spi_driver = {
 234         .driver = {
 235                 .name   = DRIVER_NAME,
 236                 .owner  = THIS_MODULE,
 237         },
 238         .probe  = spi_clps711x_probe,
 239 };
 240 module_platform_driver(clps711x_spi_driver);
 241
 242 MODULE_LICENSE("GPL");
 243 MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
 244 MODULE_DESCRIPTION("CLPS711X SPI bus driver");
 245 MODULE_ALIAS("platform:" DRIVER_NAME);